PVS-Studio warning V629 for Clang

int64_t DataExtractor::getSLEB128(....) const {
  int64_t result = 0;
  ...
  // Sign bit of byte is 2nd high order bit (0x40)
  if (shift < 64 && (byte & 0x40))
    result |= -(1 << shift);
  ...
}

This suspicious code was found in Clang project by PVS-Studio static code analyzer.
Warning message is:
V629 Consider inspecting the '1 << shift' expression. Bit shifting of the 32-bit value with a subsequent expansion to the 64-bit type. dataextractor.cpp 171

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